DIVERSITY OF ENERGY-YIELDING SUBSTRATES AND METABOLISM IN AVIAN MYCOPLASMAS

The metabolism of organic substrates and production of H2O2, a potenti al pathogenicity factor, were studied in the type strains of fourteen avian Mycoplasma species, and in low-passage isolates of M. gallinarum , M. gallisepticum, M. iners and M. pullorum. Substrates were added to cell suspensions in Ringer or saline solution and oxygen uptake and/o r change in pH monitored, The fermentative species could be sub-divide d according to whether O-2 uptake did (M. anatis, M. columborale, M. g allisepticum, M. imitans and M. iowae) or did not (M. gallinaceum, M. gallopavonis and M. pullorum) accompany glucose metabolism and the fiv e non-fermentative, arginine-hydrolysing strains according to whether organic acids (lactate, 2-oxobutyrate, pyruvate) were (M. columbinasal e, M. columbinum and M. gallinarum) or were not (M. iners and M. melea gridis) oxidized. Lysed cells of strains which consumed O-2 during glu cose or organic acid metabolism had relatively high NADH oxidase activ ity (170-950 nmol min(-1) mg cell protein(-1)) and produced 0.02-0.36 mol H2O2 per mol O-2 consumed during NADH oxidation, In contrast, stra ins which did not oxidize organic acids or consume O-2 during glucose or organic acid metabolism possessed low NADH oxidase activity (less t han or equal to 20 nmol min(-1) mg cell protein(-1)), All arginine-hyd rolysing species showed a high affinity (Km value 1-3 mu M) towards ar ginine, The fermentative species similarly showed a high affinity (Km value 2-5 mu M) towards glucose, but used only a small number of addit ional sugars at detectable rates. All M. pullorum strains metabolized sucrose (Km less than or equal to 3 mu M) The type-strains of M. galli septicum and M. imitans were biochemically similar and had high affini ties for fructose and mannose. A number of low-passage avian isolates, but none of the type strains, metabolized glycerol and, in lysed cell s, oxidized L-alpha-glycerophosphate (GP) with the production of 1 mol H2O2 per mol GP.